Screw thread tester



Dec. 1l, l95l F, SHORT SCREW THREAD TESTER I5 Sheets-Sheet l Filed Dec.26, 1945 Frm-LK E11-mrt @fw WMM/WMM Dec. 11, 1951 F. SHORT 2,577,819

SCREW THREAD TESTER Filed Dec. 26, 1945 3 Sheets-Sheet 2 Dec. 1l, 1951F, SHORT 2,577,819

` SCREW THREAD TESTER Filed Dec. 26, 1945 5 sheets-sheet s :Frank 5h nr1;

Patented Dec. 11, 1951 o FFlcE.

SCREW THREADTESTER FrankShorhQanton (felglter, Gonn Application December26, 1945, fSevriai No. 637,295

(Granted underw .the.1act of Marchf 3,' 1883, asA

The invention described herein may be manufactured and used by or for`the Government for governmental purposes, without the paymenttto me ofany royalty thereon. i This invention relates to amachine for testinthreads, both internal and external. In the meev chanic artsit isimportant, and in some situations of the utmost importance, that thethreads 1 of the parts to be untied be free from imperfections ,orfirregularities such, for instanceVas ec,

centricity to the axis of thev part, or defect inf pitch, or any of anumber of imperfections that..

occur in the fabrication of threads. The machine about to be describedis designed to detect the slightest imperfections and/ or inaccuraciesof the plates the provisionof an exact duplicate onpatf,v

tern of the perfect thread, but ofropposite hand' from the thread to begaged, and rollingV thisopf' posite hand thread in engagement with .thethread to be gaged. The result of such action,

if the thread to be gaged is perfect, will kbe no i.

movement of the indicators, Whose operation will be caused byimperfections or irregularities of some sort, and in no other way.

For internal threads, a fractional size of a per-U feet thread isemployed and placed in engage-` ment with the thread being tested,rbutin this, case the threads are of the same hand as those to be tested,and the pattern or perfect gage will have a pitch diameter apredetermined fraction of that of the thread to be tested, in order thatthe gage or pattern thread may .be moved into,A

and out of contact with the thread being tested.

In the drawings: Y Figure 1 is a top planyiew, somewhat scher; matic, ofa machine for gaging both external and internal threads, including apartly broken away j shell or workpiece suitable forv illustrationpur--Y lposes Figure 2 is a vertical section about on line 2-2 of Figure1 looking in the direction of the ar-f rows; .v

Figure 2a is a fragmentary detail section ion line 2er-2a of Figure 1;

Figure 3 is a top plan view of a modification in.V cluding a fragment oftheworkpiece and .showing amended April 30, 1928; 370 O. G. 757) themechanismffor..engagir1g an `external thread; v `Figure 3a. is an 'endlelevation of the parts b5, tween the arrows 3cr-3a of Figure 3, lookingthevdirectioniof the arrows; 'i 1 H V-`Figure 4 is averticalsection ofFigure 3 about;

Figure 4a is a` wiring Y-.diagram`l appropriate .to thei operationsoffthe;mechanism; shown in Fig uresf3zand4';

Figure 5 is a side elevation of anothermodiifjl cation showingamechanism for gagllg anhinternalcthread;y y .A 'p f Figure 6V isanelevation partly Kin-section, of modified means for vrotatingthewor1;piees, to compensate for differences V outside c liaqnetegrofthe workpiece;

Figure fisa chart of typicalierrors .W

Referring L to Y. the drawings, and particulla 1,lv Figures 1^and 2 then umeralwl` designates the.`` base of the; machine shown 'broken awayfor y economy. irrspace.4 `This will be properly .,SLIRPQFP: edvaboveasuitable supportrupon legsZLFig. 2".

LNumeral.3;.des1gnates, aworkpiece.taillis 9 i a shell, .cylindrical forthe most part, u and provid-3 ed with external threads 4 atoneendandinter?` nalthreads 5 atthe other. These threads areltne, ones tobe`testednor gagedfor imperfections of shape or location or both,obviously for, the purr-3,

showing" several indications 'pose of ascertaining whether they will`cactvpropf 1 erly and accurately with the threads of the other;elementto which theworkpiece is to bethreaded 1yv unted.- v Y 1 :The-shell ory workpiece is 4mounted for-true,

f-horizontal rotationuponits axis upon four` roll-yKV ers Bplmountednponpshafts journaled in bracketsv secured to the base as shown inFigure 2.y I AAmo'tor i and a gear reducer 8 are provided -to give aslowrotation to the shell. These may be of anyfconventional1 type, andaremounted on thee upper end ofv a web 3v whose lower end is fase.A tenedvtij-*ticeZ base I byv screws Aor other suitable J meses. J .y l

` "lhefrducer" provided with an inner `sleeve-V3 8j"; and ari'outesleeve9 in'whichthe'slow speed shaft Illisjjour'naled.v A collar ll'isprovided on'` the router endv 'of 4the shaft' and a gear wheel' I 2:vprovi'ddwithfa boss 1 3' 4is mounted on the inner Securedzte thehaft bv;.Set SQIgWS; fhiuiitiej being; such-:thatend-,wise movement 9i ,the,Sheik is prevented., V- I v y y y n.

A permanent magnet I`2' is secured to theboss- 65 I3l of. gearrwheel I2, against which theshell or workpiece may be placed to rotate the shellat a desired slow speed without slippage.

Pivoted at I to a plate on the base I is an arm I6 whose upper end isprovided with a bearing member I1 for a shaft I8 whose other end has a 5bearing in an elongated gage member I9, xed to an arm t6 '(Figure"2a?',pivotedat I6"Vv to the base in the same manner as arm I6. By .thisilmeans, the shaft I8 may be moved in an arcuate path parallel to itselfabout the axis defined by1 1Q aligned bearings I5 and I6". The member I9has secured to one side a gage havingal'polnter l 20 thereon, and aslidable spring backed contacti nger 2I. The opposite side of the dialmember is provided with a lateral extensin-which has'a'l 15:

smooth machined face 22 for contact withthe i slidable finger 23 ofanother gage 24, similar to the gage 20. Gage 24 hasa pointerl 24'..zThe. arm I6 has a lateral extension-W25' positioned somewhat above thebase 4, and having an aper- 20 tu' therethroughfor-the. passage ".of `abolt: 26 having ahead 21, whichserves asa stop to limit thecounterclockwise rocking movementof. the arm I6 as viewed at Figure.' 2.,.Interposedbef tweenthis extension 25 and thev base lI is a com- 25pression spring 28, tending. torock thearm I6, arid consequently theshaft I8 and dial member away fromthe--slidable tlnger 230i the gage 24,mounted on a pedestal 29 secured at its.lower end to#theiaase-I---u wsl-M N i.

Slidably' mounted on theshaft .I 8 isthegaging... or testing wheel 30formed with an integral sleeve 3Ito-mor`eeifectually guide the wheel inits longitudinal'emovements on thel'shaft, if thereshouldbefinJthee'tes'ting operation! occasionfor such 35 movements. Thisgaging wheel is @urged by l spring-2Bilinto--frictional engagementwiththe Yexternal threads 4 of the shell or workpiece. 3as clarly sh'own in"Figure 1, and -its threads. are oil-'opposite Vhand from thegthreads 4..The 'slid- .40 able linger 2I of- -the gage 20isin engagement wlthjtheouter smooth face of the gage wheel 30, s which-"face'liesinaplanenormallto'the axis of shaft' If'so--tha't itsmovement along theshaft I8, if' trireis -any,fduring the rotation ofA the shell. .45will'ctuatefthe finger and consequently its piritrV The wheel-30 turnswiththe external.. three/d4',` but in opposite"` direction, kand as`inti- .I m't'd, 'if th ga'ged or tested threads are accurateand inaccordancewith requirements, there will be `no movement of the `pointerof gage 20, biititthe-thread 4 should -be eccentric to the axis i of theshell, an inward and outward movement@ will'beimpartedl to the/shaft I8in parallelism witl'ltself-g and consequently there willbe a back `55and "forth Vmovementof `the pointer of the gage 24, which movement, itvwill beunderstood, will beV amplified to an extent to be clearly visibleto the operator-and thereby inform him of themaccuracyof the thread.:yNow if, the pitch di- G0 ameter of the thread 4; is .greater or lessthan that speciedthere will be/'a slow longitudinal I movement of thewheel 30 on the shaft I8.. and the, pointer` of the'gage 20 willJindicate the in-V perfection, so also 4will an irfacuate'-lad of 65thread l4 be`indi`cated. Slol'd' the'thead'engagedhave an angularitywith regard to the axis of'the"workpiece, a back and forth movement ofthe wheel 30,'"andconseduently the shaft I8, will". result, and' theimperfection will lbe indicated on 70 me gage-14;combination of errorsin the thread k4-will bel indicated by afcombination' of movements ofthe dial indicators of botli'gages 20 yThe mechanism so far describedgages or tests 75 external threads. and may be used for that purposewith or without the internal thread gaging mechanism to be described.

The bolt 26, Figure 2, extends through an aperture in the base I, wherebelow the base it is secured to the outer end of a diagonally extendinglever 3|" fulorumedfupon a'bar 32 mounted in ears 33 depending fromv theunderside of the base. The reason for the lever and its closelyassociated parts will become apparent later on. A bolt 34 passes throughan opening in the inner endo`f the lever and is held thereto by a nut,the bolt extending-upwardly through an opening in the base "and throughan opening in an extension 35 integral with and extending laterally froman arm 36, corresponding to the arm I6. This arm 36`is`pivoted at 31 toa plate secured to the base. The bolt 34 is reduced in diameter to forma shoulder below the extension 35 and carries a washer 38', betweenwhich and the extension there.:is aspring 38.Y vA cotter pin (not shown)passesxthrough the reduced endA of bolt 34 to .t

maintain the washer in position. Rigidly secured to the upper end of thearm 36 is an elongated bearing member 39 in which there is nonrotatablymounted the horizontal shaft 39 upon s which the gage wheel 4I and itshub 40 are slidableI and which functions to test the accuracy of theinternal threads 5 in the shell or workpiece 3.

vThis bearing member, like the gage member I9,

has aelateral extension 43 'with a smooth machin'ed face 44 forengagement with the iinger 45 ofl the gage 46 which carries the pointer46'. This gage is monted on a pedestal 41 on the base I, as shown inFigure 2. Spring 38 surrounds headed bolt 34, and `being interposedbetween extensionv 35 andwasher 38 tends to rock arm 36 and`consequently bearing member 39 toward the gages46, and threads 4I .intocontact with threads 5 so that rocking movement of the arm36, due toan'irregularityor imperfection in the internal thread 5r in the shell 3sensed by the gaging threads 4I, will be imparted to the gage 46 andtherefindicated by a movement of the pointer 46'.

Shouldit-be, for instance,Y that the workpiecethread is eccentric totheY axis of the workpiece, the' movement of the arm 36y will be inwardand outward with respect to the axis of the shell, the the'V` movementof the arm 36 being precisely like that of the arm I6 which functions inconnection with testing the external threads as heretoforee'scribed fThe gage wheel 4I having threads, say exactly nine-tenths of the correctpitch diameter` of that of the workpiece thread 5, is mounted on theshaft 39 in such manner that it is free to slide axially thereon andalso to move laterally parallel to itself, through the instrumentalityof the spring-urged arm 36.

Avnormal thread 5, when the workpiece is rotated, will cause acontinuous axial movement of the gage wheel 4I. This axial movement ofthe gage thread is compensated by the mechanism now-to 4be described. YIntegral with the hub 40 of the gage wheel 4I is an annular member 48having side flanges 49 between which is an annular groove'50 whichreceives the ball 5I on the end of arm 52 of a lever 53 pivoted at 54 toa block- 55`slidably mounted in a frame 56 mounted upon a pedestal 51whose lower end is secured to the base I. Mounted on the frame 56 is agage 56'havl`ng a .pointer 58', and a finger or contact element 59adapted to engage the block, there being springs 60 which urge the blockaway from the'dial' and toward a stop-6l in the frame, against Whichstop the block'restswhen not actively en' gaged in its work. The otherarm 62 of thelever 53 is traversed by a pin 63 which extends throughelongated slots 64 in ears 64' integral with ay lon' gitudinal movablesemicylindrical member 65. The' member 65 has a smooth,unthreadedinterior or concave `surface Vand isjheld inplace againstthreads 1'I or shaft 12 finjargvsuitablea manner such as by beingsplinedon'shaft* 61 xed'" in standard 66 and aided to some extent, by rodwic19. A second semicylindrical member 68 having@ internal threads, ispivoted orrshaft*Blfcrrslidf-g ing thereon as a unit with 'member 65.-Al/[emevv ber 68 is provided with a-lateral1extensionf9f Figure 2,adjacent its pivot;l whicha-'eicten'sion 1535 forms a seat for a tensionspr'ing 2i'xiterposd between the extension and anfearorxthefstai'fion-vary member 65 and tending to'u'rge' member 68 away from member 65, thatis, away from thraded engagement with sha'it- 12. is. asbestshownhinFigure -rinternally ithreaded asfatll Iand coactsi-atftims-withi-tie threads 1P; (nr-horizontal shafftr-12 fnruntederotatablybearing-13 on standardf'66 adealt i-itsethe'i end ine-bearing 14 formedat the upper end of'a stand- 25 ard'15similar tothestandard'66;'botlstardards being -securely fastenedtcal base platt-#156securedff tobase i. The standad'15is-indictedin-dettedlines /in Figurel, and-'needs nofurtherYifllust'ra` ments are to support the'fshaftvtance above the base if' f*- `IFast to the shaft-121is` a gearWheeln inmesh with the gear wheel SI2'y driven -by-" the-motor1 through thereducer 8. A lateral extensionlws :if

rod -is a 'spring 19 which. urgesthexsleeve-formed 461- byfthe members65 and`68 toward -theend-ofthe shaft 12, the head on the rod19-limiting-lthelout-i' Ward movement of the sleeve by engagementbeatween the said head and the extension 18. 'L'I' ther widened portion 8lfcrfsljidin'g-y eng-agemenawith the threaded member68= tof-iat;appropriate times# move' said member' Yover land against the ythreads 1Iof the shaft 12 against the actionfof sp'rin'g-1`0-L 1 tocause movementof the-A 'sleeve onf-the shaft when the shaft'is rotated,A therebyVAtorock-`the lever 53 so that the blocllz'wvillfoperatestliefiinf4ger-59' of gage 58 toin'diatelth-elrigitudinalf uctuatonsbfthegaging-whe 4IH he :lever 4NIx has'- a narrow*handleJ82adaptedf-to' Y""fe the other of two e shallow -notches'83 841 of a standard l86mountd'cn? he ase "Ifto" hold member 68 in'orout ofengagenient with thethreads of shaft 12A`as desired y `Inthe position shown thethreaded'mmberl-GB66 isfY out of engagement Vwith thel `threadsilli'andAshaft*4 12, and cons.equently-`=tlie' sleevaz:'.Wmgnoty be' moved bythe:rbtation-of'thshft; utiing thegaging'operationthesefthreadslwillibee il* gagement andv v onfthe shaft at a ratecalclate'd 1pc-"corpe'nsate.flr for-the normal outward'ftra'velfof thegg' wheeli Mswhen the thread 'tv of thewerkpieeefiseffect:v rect dimensions. `'Ihe4mov'e'x'ne'rit'ofYthe sleeve is determined bythecarefulcalculationloftlie pi-tcf:l1*'70 ofthe thread onlthe`sh'aft312C tl-'ievptchd" ameters of gear# wheelsI iA y Wllfieril'the?sleevehas'freachedtliel'liinitc lits predetermined 1u te epen positioninte recess so' behindaeshnreeeivetede thefsn'ftf' The member 68 20arrivage1a?rr 6 der 80" of the lever 80 with the block v55 againstthestopil. e

The numeral 81 indicates a plunger having an operating head 81'. A boss88 on the base has an opening therethrough forV the plunger whichplunger also passes through an opening-in the base -l with its lower endin position to engage the lever 3 l' to depressl one end of theleveragainst the influenceof the spring 28 andto simultane- 'ously raisethe other end and release thetension of the spring 38, this operationbeing for the purpose of rocking and holding the gaging wheel 3|) awayvfrom the shell or workpieceand also the gage wheel-4l v-away'f-rom theinternal thread 5 of the work to permit withdrawal or insertion of theshell, as may be required. The boss 88 is provided with a bayonet-slot89 coacting with a crosspin 86 to hold the plunger in raised or loweredposition as desired.

The operation of the'mechanism thus far described has been indicatedtosome extent' as the i description proceeded, but Vat the risk ofrepetition@ and for the sake o-f clarity,it -is summarized.;lv Thegaging wheeli-30 turns. with'- thread# 4 but in# opposite direction.*vIff the desired factors oifthe gagedsthread` 4 are.. in accordancewith theA re. quirement, `there will be no nmovement--ofi-thejindicators 20' and 24. If the thread 4 is eccentricV with respect tothel axis of--the work-or-shell 3,gshaft I8 will be rocked--orrscillated, -in-paral lelism with itself, withr'espect to the'axisot-the# shelland an amplied oscillatory movement of the pointer 24 ofdial24wifll occur.M I-f the pitch of -the thread` v4 is greaterthan orlessl than specified, therewillbe'a slow-lon`gitudinal movement in onedirection or the-other ofi-the`A wheel 30 on the shaft which will-'beshown by'- the pointer 26 ofthe gage 20eSo'alsa-williai faulty lead ofthread-4 be'shwn; A gagedr threadY having angularity offits axis willcause aback and forth movement of the Wheel 30,`which willi be shown ongage 20. Should there bea plurality# of errors they will be indicated bya combination@ of movements of the pointers of'b'oth' gages'.4

YForgagingoperations' `of the internal threadafi the gaging wheelVfl'I-isplac'ed at"'thefinnerfend-' of the--threadr in the shell and thenarrowe'end/ of lever 86 is moved over into inner notch 83 ofthe head84, closing the member 68 againstith'efi threads of shaft 12 and holdingit in such engagement. The rotation ofy the shell 3 willA now cause?gage wheel 4I tov moveslowly outwardly moving? the "sleeve formedyby''the'memb'ers 65 -an'd 6BV inwardly at the same ratesoth'attheris-ne---f Hmoyementofthe pointer 58 ofthe-gage-", Tprovidingthe thread 5 is correct. If the 'shell thread has an incorrect lead, thepointer 58 will indicate thefault by a continuous lateral displacement.4If-the axis of thread 5 is angular with respect to the axis of theshell, the pointer 46will show it@l byan oscillating movement. If theYthread 5 iseeccentric tothe center line of theshell, the pintera-f (2 sin.' nig.' yl i Tp-o fgrm hg gagwwlieel 'Mpls npr'oideleeeeiedipieierk.Whieesneebee wither? .ieler meeriteeeglenefeeeefeeh, t eegiegfbyrthedirrn 99 of gage/member. |001`n which the shaft vfnlii1td`and.secured,"asffinstaric,by;` set sci-ewl'l'fIli's'iaftieisfixed izfmeinlgr f screwV v|l|2 and lcarries a gage 1073"4 plfeiiegwiihHilger |06 iaeneeeemeflt .with ilie.` f eiaegeihe gege 4wheel .3.0, .andwith @gelet-er. '93j Thefwier, end` ef tbeeege, member .l 09 vhee e.SmeQtb-.meehined .fece eesejgediby teenager U51. i aegee.- l, Hering, apointer. |052' and; meunted- 0n the .yupperend Standard or vpedestal401.. Seemed-t0 thebese; l ...-{Ilhearm 9| has two lateral extensionsintegral thexeivitlly;... ne\ |.98.; .tfthe= left.Ak and. 4the. other.|09, at the right as seen at Figure 4. A spring I|0 connected to theunderside of extension |09 and to the base tends to pull the extension|09 over against an adjusting screw l|| in an internally threaded post||2 on the base to thus move wheel 30 away from threads 4. The extension|09 is attached to the armature of solenoid |08 which when energizedovercomes the spring ||0 and holds the wheel 30 against the thread 4 sothat the threads of said wheel will properly engage those of the work.Suitably supported by attachment to a collar |50 fixed to a sleeve |5|of gage |03 is another solenoid ||3 whose armature ||3' is positioned toengage the finger |04 of the gage |03 under the influence of spring ||4.When the solenoid ||3 is energized, the armature is pulled away from thefinger |04 so that it may function in the usual manner to indicate thelongitudinal movement of the gage wheel 30 along its shaft 93 during thegaging operation. When solenoid ||3 is ie-energized,

armature ||3 is urged by spring ||4 into frictional engagement withcontact or finger |04 to thereby hold the latter in any position towhich it may be moved. Thus, at the completion of a gaging operation,wheel 30 is moved out of contact with threads 4 by pivoting its shaft 93about the axis of shaft 89'. The wheel is then moved to its initialposition to the right as viewed in Figure 3. This movement also movesfinger 04 to the right and because of the action of spring ||4 andarmature ||3, the spring-pressed finger is restrained from moving wheel39 to the left until such time as solenoid ||3 is again energized. Asolenoid arrangement like that justv described may be employed inconnection with the finger |05 of dial |06.

The supply of electric current to the solenoids |08 and I3 is controlledby a switch 5 mounted on extension |09 of arm 9|, and carrying contactbuttons |6 and ||1 engageable by a pin |I8, carried by the idler wheel91. The ratio between the number of teeth on the pinion and those on theidler is such that a'given number of turns will be accomplished by thegage wheel 30 between the time the idler pin |8 presses against thebutton ||6 and the time it engages the button ||1. Obviously the pin ||8may be adjustable or added pins may beV employed to control at will thenumber of turns of the gage wheel, and a number of turns below themaximum.

As may be seen upon Figure 4a, solenoids |08' and ||3 are connected inseries with a battery |52 and a switch ||5.v This switch has buttons ||6and ||1 which, when in the position shown, close the circuit. However,pressure upon either button acts to open the circuit through solenoids.r' al f. 1, l e staftortepdifl'nggopeaoa gear 91 'is in position sucli,i'lilljiiL-Tis l in contact Awith litten iii, and the" circuit isaccordinglyvop'e 'Springfflthusacts to hold wheelzljfp'tgf centacfwith.the threads f workpiece onsupprting rollers 6 while armature I3 acts tohold finger |04.in retractedposition.' The workpieces nowrotated andfa'spin ||0 movesfaway from .button IIB, the latter nievesl euiwedlyrf weleeei the Seleneid eifeit' .Enerf'r gizetie 0f Solegod |8.,ln0ves.Wheel -f 302.1999; engagement witl threads .4-.yhi1e eiiefeietiet.OffeQleeQie I liza-liberare. armature 'f 'I 'I3'- errer permite.I linger|04 te. meveinte @gesegnet-Wiebe thg''fceof WhekaarAf-ftr aupedermmdffnumber of rotations ot the workpiece and wheell 30, pin ||8 engagesbutton ||1 and opensthe circuit. During the rotation of the workpiece,the gages |03 and |06 operate in the manner described for gages 20 and24, Figure 1. The rotation of workpiece 3 stopped as soon as button` ||1is pressed inwardly, spring ||0 now acts to move wheel 30, out ofengagement with threads 4 while spring ||4 acts to yieldingly fix fingeror Y feeler |04 in position. The workpiece is removed, wheel 30 slid tothe right, Figure 3, to initial position. This movement also movesfingerv |04 to retracted position in which position it is now held by,armature ||3' and spring ||4.- Switch |53 is opened, idler gear 91 isrotated to bringey pin ||8 into initial position wherein it holds button||0 depressed, a new workpiece is placed. switch |53 is closed, and thecycle just described is repeated.- In the wiring diagram, Figure 4a,coils are shown corresponding to the solenoids |09' and |3. As stated,another solenoid, like ||3, may be included in the circuit with itsarmature engaging the nger |05 of the dial shown in Figure 3, all of thesolenoids being energized and deenergized simultaneously by the closingor opening of switches |5vand |53, as previously described. v

Modification` Figure 5.-In this modification an arrangement is shown fortesting an internal thread. There is a suitable base I9 upon whichstandard |2| may be secured and provided with roller bearings` 6 at itsupper end suitably 4spaced to bear evenly upon and support the shell 3,which in this case is supported a substantial distance above the base. Ashaft |22 is rotatable in bearings |23 and |23 on standards |24 and |25secured to or resting upon the base H9.

The shaft extends beyond the bearing |23 and has an additional supportin the bearing portion |26 on standard |21 xed to the base. There is agage |28 on the upper end of this standard, which gage is a duplicate ofthe others that have been heretofore described. It has a contact fingerindicated in dotted lines, which in this form engages the smoothmachined face |29 of a gage member |30 formed at the upper end of arm|3|, the lower end of the arm having an integral'hub |32 journaled uponthe shaft |22. YThe gage member |30 which is mounted on the arm |3I, andvirtually a part of it, carries a gage |33 whose finger |34 engages thesmooth side of a gear wheel |34' rotatably mounted on a stud shaft |35carried by the gage member portion of the` rockable arm |3|. The hub|35' of gear wheel |34' carries the gage wheel. y 4| in engagement(during the testing operation) withY thev internalthreads 5 of the shellor workpiece I.

Mounted on the shaft |22 and rotating with it, is a gear wheel |36having a broad face so that gear I 34 may have ample movement axially ofshaft |35 while remaining in mesh with gear |36. At the other end of theshaft |22 and beyond the bearing |23 is a gear |31, also fast to theshaft and meshing with a gear |38 of the same size and mounted upon theshaft of the reducer |39 mounted upon a pedestal |40, or upon any othersuitable support, maintaining it at the proper elevation relative to theother mechanism.

The arm |3| may be biased toward thegage |28 by a spring 4| secured toan ear I5!) on the hub |32 and to an eye |5| onfthe base IIS, or byother suitable means, the requisite beingthat lateral iiuctuations ofthe arm will be indicated on the dial |28. In this form the threadengaging member 4| may be nine-tenths of the correct pitch diameter ofthe workpiece threads and is positively driven at the same angular speedas shell 3 so as to have some slippage with respect to the thread 5. Thearrangement preferably is such that the gear wheel |38 drives the gearwheel |31 at a one-to-one ratio, and the broad face gear |36 drives thegear wheel |34 also at 'a one-to-one ratio, thus causing slippagebetween the gage wheel 4| and the internal threads -5. Bv thisarrangement-the angular relation of -the threads 5 of the workpiece andthose of the gaging wheel will remain constant rather than their linealrelations. So that the angular relation between the threads be notdisturbed, I prefer to mount the arm `|3| carrying stud shaft |35 onwhich is mounted the gage wheel 4| and its hub and gear wheel |34', sothat there will be no change in pitch diameter relationship between 4thegears |34 and |36. The gage |33 mounted on the gage member |30, whichmember is or may be a part of the arm |3|, will measure the axialmovement of the gear |34', and the gage |28 mounted on fixed standard|21, will measure lateral movement of the arm |3|.

Slight differences in outside diameter of the shell or workpiece willaffect the axis of rotation of the workpiece. To compensate for this Imake the connection between the magnet |4| (Figure 5) and gear |38(Figure 5) somewhat diiferent as will appear from Figure 6. In this formthe magnet |4| which engages the end face 4 of the workpiece is providedwith the hollow hub |42 of much larger internal diameter than thereducer shaft |43 to which the gear wheel |38 is fast. The magnet ismounted on the shaft by a plurality of rings |44, two in the presentinstance, of

resilient material, and the hub |42 of the magnet and hub |46 of thegear wheel |36, are each provided with intermeshing clutch teeth |48between which there is some play, which with the yielding rings producesa positive drive with enough iiexibility, to compensate for slightoffset of the axis of the workpiece with respect to the axis of theshaft |43.

In Figure '7 is shown a chart showing several indications 'of typical.errors. TIhecurves are plotted for time in revolutions indicated bycharacters 0-5 at the topl of the chart, for the abscissae and pointerpositions as ordinates. The movement of the pointer of the dial 24 isshown in solid lines, the movements indicated by the pointer of dial`2|), being indicated Ain dotted lines. The combination of movements ofthe two indicators referred tov give distinctive indications of theseveral errors to be found andthe accumulations oferrors in. five or anydesired number of revolutions maybe seenrat a point of l supporting theworkpiece for true rotation upon f' its axis, means for rotating theworkpiece, a gage wheel having perfect threads, the counterpart of.which is desired in fthe threads of the workpiece and engaging thethreads of the workpiece, pivoted means mounting the gage wheel forlateral movement relative to the axis of the workpiece,

means mounting said wheel on said pivotal means for rotation and axialmovement thereon, means associated lwith said pivoted means fornorn'ially` urging the gage wheel into engagement with the threads ofthe workpiece, means carried by said pivotal. means mounting and inengagement with Isaid gage Awheel to visually indicate axial movement ofsaid wheel, and means xedly mounted adjacent and engaging said pivotedmeans for visually .indicating the lateral movements of said gage Vwheelin response to the movement of saidpivoted means imparted by thegage.Whee1,.y i 2.- In amachine zforntestingfthe threads-of-a threadedworkpiece for detection of imperfections inthe threads-,ofthe workpiece,means for supporting the workpiece for true rotationupon its axis, meansfor-rotatingthe workpiece,v a gage wheel having -perfect'threads thecounterpart of which is desiredA on` the threads 4of the workpiece andengaging the threads ofthe workpiece and ing the gage Awl'ieelforlateral movement relative to the axisL of thefworkpiece into and out ofcontact with the Ithreads thereof, means mounting .said gage wheel. on.s aid pivotal means for rotation on andsliding .along an axis parallelwith theaxisof rotation of said workpiece, an indicator on said pivotedmeans and having a member engaging. the side of the gage wheel,saidindicator beingv responsive through said member to the sliding.movements of the gage wheel, anda second indicator adjacent and engagingsaid pivoted means thereby to indicate the lateral movements ofthe gagewheel.

, 3. In a machine for testing the threads of a threadedworkpiece, meansfor supporting `the workpiece for true rotation upon its axis, means forrotating the workpiece, a gage wheel having perfect threads thereon, thecounterpart of which is' desired in thev workpiece threads, means forholding the gage wheel threads in close frictional contact with thethreads ofthe workpiece, means mounting the gage wheel for longitudinaland lateral movement relative to thc axis of the workpiece, andindicatormeans for indicating said movements ofthegage wheel. y A

4. Ina machine for gaging the external threads of a threaded workpiecefor the detection of imperfections in the.,workpiece threads, a gagewheel having threads the exact counterpart of those'desired in theworkpiece and of the same pitch diameter and. adapted to frictionallyengage the threadsof the workpiece, means for supporting the workpiecefor true rotation upon its axis, meansjor ,rotatingA .the workpiece,means mounting-dimage@ whel. for longitudinal Vand latral movement inparallelism` with the workpiece mamar-9 fil axis, and meansforindicating such movements of the gage wheel',Y i

5. In a machine for gaging the external threads of a threadedworkpiece'for the detection of imperfections inthe workpiece threads, 1

a gage wheel having perfect threads, the counterpart of which is desiredin the workpiece, means mounting the gage wheel for longitudinal andlateral movement relative to the axis of the 'workpiece means forindicating such movements, the threads on the workpiece and those p onthe gage wheelgbeing opposite hand and of the same lead and pitchdiameter so that when the threads are rolled in contact only imperfecjtions in the workpiece threads will cause longitudinal or lateralmovement of the gage wheel Y and consequent actuation of the indicatormeans. 6. In a machine for gaging the threads of an internally threadedworkpiece, means for sup- -porting the workpiece for true rotation onits 020 axis, means for rotating therworkpiece, a gage wheel havingthreads thereon the counterpart of which is desired in` theworkpiecetthreads, said gage wheel being smaller in diameter than thethreaded opening ofthe workpiece and of the 625 correct leadrand pitchdiameter of the workpiece threads and in engagement with said threads,means mounting said' gage wheel for rotation and longitudinal andlateral movements, means for indicating the longitudinal and lateralmove- U30 ments of the gage wheel, andconnections be- 'tween saidindicating means and the gage wheel whereby said means is operated toindicate such movements upon the rotation of the gage wheel.

'7. In a machine for gaging the threads of -an L35 internally threadedworkpiece, means for supporting the workpiece for true rotation on itsaxis, means for rotating the workpiece, a gage wheel having threadsthereon the counterpart Vof which is desired in the workpiece, meanslilmounting said gage wheel for rotation and longitudinal movements, saidgage wheel being smaller in diameter thanthe threaded opening of theworkpiece and having threads o f the correct pitch diameter of theworkpiece threads and in engagement with said threads whereby when theworkpiece is rotated the gage wheel will be rotated andi movedcontinuouslylongitudinally in a direction'axially of the workpiece, ashaft rotatably supported in parallelismv with -the axes of the gagewheel and workpiece and provided with threads, a threaded sleeveengaging and moved by the threads of said shaft, c011- nections betweenthe workpiece rotating. means Aand the shaft whereby the shaft isrotated in -timed relation with the workpiece, connections -between thesleeve on the shaft and the gage wheel constructed and arranged tosubtract the axial movements of the gage wheel from the correspondingmovement of the sleeve, and indicator means associated with saidconnections to indicate any difference in said movements.

8. In a machine for gagingH the external threads of a threaded workpiecefor the detection Aof imperfections in the workpiece threads, means forsupporting the workpiece for true rotation 'upon its axis, means forrotating the workpiece, a rockable member adjacent the workpiece andmovable to and from the workpiece, a shaft mounted in said member inparallelism with the 'axis of the workpiece, a gage wheel rotatable andslidable onsaid shaft and-having perfect threads the counterpart ofwhich is desired in the workpiece and adapted to engage the workpiecethreads and rotatablethereby; said g'ag'wlie'el vbeing provided with anelongated pinion, al gage member fast to the shaft,,indicatormeansfcarried by the gage member and'having a ngcr in engagement withthe side of the gage -wheel and moved thereby to indicate thelongitudinal movements of the gage wheel, if any, an idler gear carriedby the Vgage member and in gear with said pinion and rotated thereby, anelectrical circuit including a magnet adaptedwhen energized tourge therockable member toward the threads of the workpiece, a switch in thecircuit actuated by the idler rwheel to open and close said circuit; andspring means arranged to urge the rockablemember and-gagewheel away fromthe workpiece when the Vmagnet-is de-energized. --f' 9. In a machine fortesting screw threads. means adapted to mount a workpiece for rotationabout the axis of an internal thread ofsaid workpiece, aV hub havingexternal threads of the same lead as said workpiece and a pitch diameterequal to a known fraction'of the corresponding diameter of saidworkpiece thread, means 'mounting said hub'for rotation on a second-axisparallel to saidr first-named' axis with said threads inengagement, ablock translatable parallel with said axis, lever means pivoted on saidblock, `a pivotal connection between one end of said lever meansandsaid' hub, means pivoting the other endof said lever means in timedrelation with the rotation of saidworkpieca and means'measuring anytranslation of said block as a criterion' of thelead of the threads ofsaid workpiece.n Y Y l Y 10. In a'machine fortesting the threads ofathreaded'workpiece, means for-'supporting the workpiece for truerotation'upon its axis, means roperable to positively rotate theworkpiece about its axis while so supported, aY gage wheel havingcircumferentially completel perfect threads the counterpart of which isdesired in the threads of the workpiece, means mounting said wheel toengage the workpiece threads in pure tangential rolling contacttherewith, for axial translation andfor lateral rocking movement towardandv from the workpiece about an laxis parallel with the axis ofrotation thereof, and 4means responsive to axial translation and lateralrocking of said gage wheel to separately indicate suchmovements.

11. In a machine `for gaging the-threads of an internally threadedworkpiece,- -means for supporting the'workpiece for VYtrue rotation onits axis, power-driven means-for rotating the workpiece, including`afirst A gear having operative yconnections with the workpiece, a firstshaft mounted for rotation in Aparallelism withthe axis of theworkpiece, a second gear on said shaft in meshwith said first` gearwhereby said shaft is rotated in timed relation with the workpiece, anarm rockably mounted-cn said first shaft, a second shaft carried by saidarm, a third gearslideably,and ratatably mounted on ,said second shaft`:and having an integraly hub,

a gage wheel xed on said hub and havingpervfect threads the `counterpartof which is desired 13 workpiece having a rst axis, said threads beingsupposedly co-axial with said axis, means mounting said workpiece forrotation only on said first axis, a shaft, means mounting said shaft inparallelism with and for movement toward and from said first axis, agage Vwheel having perfect threads the counterpart of those required insaid workpiece, said gage wheel being mounted for rotation and axialtranslation on said shaft, first gage means responsive to sliding ofsaid gage wheel along said shaft, and second gage means responsive tochange in separation of said rst axis and the axis of said shaft.

FRANK SHORT.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Number Name Date Johnson June 9, 1931Hartness Nov. 3. 1931 Garms et a1. Apr. 18, 1933 Beardsley Dec. 19, 1933Zerkle Jan. 7, 1936 McClure Mar. 4, 1941 Weinthal et al. Dec. 23, 1947Johnson Dec. 30, 1947 FOREIGN PATENTS Country Date France Apr. 26, 1932

